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"TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

The item is a "TEG Power" 12 volt (15 watts) thermoelectric generator that retails at $289.99. It operates by sitting on top of a woodstove and converts heat into electricity that can charge a 12 volt battery.

The TEG Power company is based in Morgantown, WV, and looks to be a small but ambitious outfit with good ideas. But how practical is their product and how well does it deliver?

For years I've thought that a generator of this type would be the perfect thing for a small off-grid 12 volt PV/battery homepower system like mine. This time of year of short days and lots of clouds and overcast weather in Northern Wisconsin provides very little PV electric power generation and I am forced to run a gasoline-powered generator. But at the same time my woodstove is fired up and hot 24/7. A near continuous 15 watts would help my battery bank alot when my PV array is putting out almost nothing.

Heck, we're even talking about the charging the battery at night!

A Google search doesn't turn much up about this unit or the TEG Power company in general. One party in Alaska had trouble getting the product delivered and after much delay got a refund. That does not sound very encouraging. Nor does there seem to be anything else like this on the market. Gotta wonder there too. Because a 12 volt thermoelectric generator working off a woodstove seems to be an ideal thing for a small off-grid PV system like mine and I can't be the only one also heating with wood.

You people know a lot more tech stuff than I do so any comments or information would be much appreciated. I'm ready to buy one of these units as $289.99 plus shipping is reasonable, but I don't want to be ripped off or vastly disappointed either. Please help.

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

Sounds like a Seebeck sandwich to me. This is what powers the Eco fan, and that works. But has tiny power demands compared to recharging a 12 Volt battery.

I doubt this is a thermionic generator, although they'd like you to think it is.

This claim bothers me: "PV panels typically produce about 0.0036 kWh per rated watt"
Really? Try putting them outdoors in sunlight instead of in the basement under a tarp. Mine produce 4 W hours per rated Watt in the Cariboo. If they're telling lies like that they are most likely selling a piece of junk. The claim that this thing is equal to a 100 Watt panel in S. Cal. is suspect. Such a panel would produce 385 Watt hours per day. Their device @ 15 Watts over 24 hours: 360 Watt hours, if it could maintain its maximum output (as opposed to the derated number for the panel).

The price is about the same as a 140 Watt Kyocera. From that POV it doesn't look like a good value to me, even if it did work. I see no mention of it being charge regulated either. It does say the output is 13.9 Volts, which is okay for floating a battery but insufficient for charging it (especially a deep cycle).

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

This TEG is a lower-powered version of our Source-1 TEG designed specifically for charging 12 volt DC batteries. Easily charge any 12 volt battery from any horizontal heat source of 350F or greater. This is a Plug n’ Play device. No cooling system or wiring to mess with, simply place the TEG unit on a wood stove, camping stove or other heat source and hook the clamps to your battery. Have emergency backup AC power when you need it by adding an AC voltage converter and any 12 volt battery to our 12 Volt TE Battery Charger! Being prepared will not cost you an arm and a leg!

Solar Comparison: Solar PV panels rarely operate at the full rated power output. In the real world, PV panels typically produce about 0.0036 kWh per rated watt, per day if operated in sunny Southern California. Since we do not all live in California, one should expect even lower daily output. Our 12 Volt TEG Battery Charger (rated at 15 watt), operating continuously on a wood stove for one day is the equivalent to a 100 watt solar photo voltaic panel operating for one day in sunny Southern California. Note: Figures based on real world performance data supplied by manufactures.

If you can keep a stove at 350 degrees F 24 hours per day--Then, yes, it appears that it will meet its specifications.

Second, I do not like the " 0.0036 kWh per rated watt, per day" number... kW/W is just throwing a factor of 1,000 confusion in there... If they said 0.36WH/W of panel rating per day--I could buy that:

So, using the above, I would even use a larger derating number than the website lists...

There is no charge controller and only you know if you can keep a stove operating at 350F+ for long periods of time. It is not energy efficient, but it is "free" if you need the heat.

I would be careful, TEG modules do not like heat and will probably self destruct if overheated (fan fails, something covers fans, stove gets really hot, etc.). 500C (932F) is a pretty high max temperature rating--Hopefully, it works fine for years to come.

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

Keeping the stove top 350f for even 12 hours a day, would roast me out! For 15 watts, I would make. Bicycle driven genny, and get my 100wh that way...or just use a 100 wtt panel, a less than half the price!

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

tegs may be fine to play with, but don't design a whole system around it as it won't work out for you. one of them may put a few insignificant float charging watts toward a regular system and often a voltage upconversion is needed when only one or 2 are employed. the guys are correct that these things are picky, but can work on a very very small scale if planned out right. is it worth the effort? i'd say not as i considered doing that years ago, but on an experimental basis you can play with them.

btw bill, even you got confused as that would've translated into 3.6wh. that proves that their tactic does work even on those familiar with the way kw and w work as it increases the chances of a mathematical error and you to less likely get a proper perspective. you also meant to put per day on the end of that

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

yes, that is essentially what they are. the series connections would up the voltage, but it will require more physical room to attach these to the heat source. way too many would be needed for it to be relied upon as a significant source of power.

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

And because someone felt it necessary to "correct" me when I mentioned this in the "short form" on another thread ...

Technically this is the Seebeck effect; converting thermal conduction into electrical current. Peltier is the other way around: converting current into thermal conduction (think of those coolers for cars). They are usually thought of together as "Peltier-Seebeck" but even the companies that make devices using this dual principal (including Eco fan) just call it by the shorter "Peltier".

You usually get <2 Volts from a typical sandwich, and only a few mA of current. Likely this would have about 8-9 in series to produce that 13.9 Volts, and possibly another parallel set to get enough peak current to make the 15 Watt (under perfect conditions) claim. Most likely it's all done in one custom-made sandwich.

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

One application where these might make sense - powering a small circulating pump in a woodstove hot water heater coil set up that cannot rely on thermosiphon.

BTW - I have one of the Biolite camp stoves - which combines a jet stove design with a termoelectric generator to power a small fan and charge usb devices. It works great as a small woodburning camp stove - but it's usb charging capability is pretty limted. The last time I used it I burned a whole lot of twigs and heated a whole lot of water just to maintain a minimal charge on my iPhone.

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

I see they use these in some crazy solar concentrator projects in the desert in the USA, saw some stuff on Discovery the other day about them really cool...series of mirrors bouncing and concentrating the sunlight onto the engine to make steam to drive it...darn cool!

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

Unfotutunately the firm that was going to commericialize the Sandia Lab Sterling Cycle units went bellyup, another firm in a long list of Sterling Cycle generators that werent quite ready for pirme time.

There used to be an Icelandic firm that sold TEGs for woodstove use. The firm's name was very icelandic and I think Home Power had a articel about them at one point.

Re: "TEG Power" 12 volt Thermoelectric Battery Charger--Any good?

The 350 F. temp necessary to run this thing at peak 15 watts and no chart showing a temp/output curve raised red flags for me. So did the lack of testimonials or feedback about this device. Also a lack of similar products on the market. But you guys put it all in very good perspective and others may benefit from this thread.

Electricity from a woodstove is still a very good idea but it's time is not yet come--so it seems. But I sure do HATE running that generator which I have been forced to do lately. PV just isn't very good this time of year. Although the sun is out today. Yippee!